Floating liquid monitor

ABSTRACT

Apparatus for detecting the presence of a reflective liquid of lesser density floating on a more dense liquid of different reflectivity wherein the intensity of a beam of reflected light is measured to detect the presence of less dense liquid.

O United States Patent 1151 3,659,943 Goolsby 1 May 2, 1972 541 FLOATINGLIQUID MONITOR 3,309,956 3/1967 Hach ..356/103 3,417,251 12/1968 Leonardet al.... ...356/l03 X [72] Gwlsb Mmga' cam 3,490,849 1/1970 l-lambleton...3$6/2l2 x [73] Assignee: Shell Oil Company, New York, NY. 3,528,7509/1970 Hach ..250/218 X 2,406,166 8/1946 Scott... ..3S6/2l2 [22] 19702,546,450 3/1951 l-lunter.... ...356/2l2 21 Appl. No.: 3,161 3,549,26112/1970 Hacll ..356/195 [52] U 5 Cl 356/70 250/218 356/72 FOREIGNPATENTS OR APPLICATIONS 356/103, 356/104, 356/208, 356/209, 356/212251,919 1/1967 Austna ..356/l04 [51] Int. Cl. ..G01n33/28,G01n21/48,G01n 21/06 58 Field 61 Search ..356/70, 72, 102-104, 'wDrummer-Ronald Wlbefl 35 6/2084 1 2; 250/218 Assistant Exammer-Warren A.Sklar Anorney-T. E. Bieber and J. H. McCarthy [56] References Cited [57]ABSTRACT UNITED STATES PATENTS Apparatus for detecting the presence of areflective liquid of 2,060,957 11/1936 Tarvm et a1 ..356/209 X l sdensity floating on a more dense liquid of different 214011929 6/1946Hammond, -250/218 x reflectivity wherein the intensity of a beam ofreflected light is I? gtk l 1 4 i: measured to detect the presence ofless dense liquid. tar et a 3,278,753 10/1966 Pitts et a1. ..250/2181lClaims,3 Drawing Figures /1e-| 3O 4e 23 24 41 I I 1 M 2e 5 l g g i 2829 4 i 1 25 1 1; 1 27 51 22 T F 11 I y 1 l 115, i

14 37 21 it} Zlq 1 Jag-7777 L i J Q 38 l 44 39 Patented May 2, 1972 I3,659,943

2 Sheets-Sheet 1 H l l F|GI 2 INVENTOR;

A. D. GOOLSBY BY: Hl -fl HIS ATTORNEY Patented May 2, 1972 2Sheets-Sheet 2 LLLL A. D. GOOLSBY INVENTOR:

HIS ATTORNEY FLOATING LIQUID MONITOR BACKGROUND OF THE INVENTION 1.Field of the Invention This invention relates to an instrument formonitoring the surface of liquids to detect the presence of less densefloating liquids.

SUMMARY OF THE INVENTION The object of this invention is to detect thepresence of a reflective liquid of lesser density floating on a moredense liquid of different reflectivity, for example, to detect thepresence of oil on water. This objective is achieved by measuring andrecording the intensity of a beam of light reflected from the surface ofthe liquid to be tested. An appropriate increase or decrease in theintensity of the reflected beam is indicative of the presence of thefloating liquid.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic perspectiveview of the side of a preferred embodiment of the invention.

FIG. 2 is a horizontal section of the preferred embodiment of FIG. 1taken on line 22.

FIG. 3 is a circuit diagram of the preferred embodiment of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1, 2 and 3,the electrical components of a preferred embodiment of the invention areenclosed in explosion-proof housing 20 which is provided with apertures40 and 41 and adapted to be mounted above a turbulence reducing bafflemeans 10. The baffle means at least a portion of which extends beneaththe surface 39 of the liquid to be tested may be provided with ports 42and 43 through which liquid may pass into and out of a fluid channel 47.This baffle means 10 may be operatively connected to the housing 20 byconnecting means, such as bolts 21 and 21a. The housing 20 may also beaffixed to a buoyant substructure 38. A light source 12, which may be inincandescent lamp preferably powered by a constant voltage transformer27, is affixed by support means 45 to a partition 19 which separates itfrom a reference lightsensitive pickup means such as photojunction cell17. The partition 19 is provided with an aperture 18 and preferablycarries an adjustable aperture means such as flap 46. The referencepickup 17 is positioned to receive light passing from the light source12 through the aperture 18. A converging lens 13 is positioned betweenthe light source 12 and the water surface 39 to cause approximatelyparallel rays of light to strike the surface 39 39 preferably at anangle of incidence of 0 to 20 1 6 in FIG. 1). A light path window 14which covers aperture 40 may be recessed and heated by a window heater15 to reduce condensation where present. A sample light-sensitive pickupmeans such as photojunction cell 16 is oriented to receive lightreflected from the liquid surface 39 at an angle equal to the angle ofincidence. A converging lens 37 may be interposed between the samplepickup 16 and the liquid surface 39 to focus reflected light on thesample pickup 16.

The sample and reference pickups, 16 and 17 are disposed in adjacentlegs of a bridge circuit 33 which may be activated by switch means 24.Bridge circuit 33 is coupled to a variable gain amplifier circuit 35,the output of which may be filtered to remove small scale signals due tosurface turbulence by filter means as, for example, a capacitor filter36 or a peak picking circuit. The bridge amplifier 35 is in turn coupledto a recording device such as signal meter 29 and to a process alarmamplifier circuit 34 which may be an alarm circuit that provides anoutput only if the input into the circuit exceeds a preselectedmagnitude. This threshold magnitude may be regulated by means such aslevel adjust potentiometer 22 which is controlled by a level set controlknob 48. An alarm display means such as an alarm meter 28 or a light orhorn may be coupled to the process alarm circuit 34 to indicate theoutput thereof. The bridge amplifier 35 and process alarm circuit 34 maybe powered by means such as power supply 26 which rectifies a.c. currentand may be carried by a circuit card 25. The apparatus may be turned onor off by switch means 23. Meter viewing window 30 over housing aperture41 provides visual access to alarm meter 28 and signal meter 29.

The apparatus of this invention provides means to detect the presence ofreflective liquids of lesser density floating on a more dense liquid ofdifferent reflectivity, for example, to detect the presence of oil, amore reflective fluid of lesser density, floating on water, a lessreflective fluid of greater density, in refinery effluent systems or indock areas where oil spillage is a problem.

To prepare the apparatus for operation it should be placed in the liquidto be tested with switch means 23 and 24 turned to the on" position. Thebridge circuit 33 is then preferably balanced with only liquid ofgreater density passing through the baffle means. Balance is achieved byregulating the adjustable aperture means 18 until equal amounts of lightstrike the reference and sample pickups 17 and 16. This status isindicated by a null reading on the signal meter 39.

In operation, liquid enters the fluid channel 47 in baffle means 10through port 42, passes through a region of light reflection 11, thenpasses out of the device through another port 43. As the liquid passesthrough the region of light reflection 11, light from the light source12 passes through the converging lens 13 and the light path window 14 tostrike the surface 39 of the liquid to be tested. A portion of thislight is reflected from the surface 39 along a light path 44 passingthrough light path window 14 and converging lens 37 to be focused on theface of sample pickup 16. As long as the reflected light striking samplepickup 16 and the light passing from light source 12 through theadjustable aperture 18 to strike reference pickup 17 are of equalintensity, bridge circuit 33 remains balanced. However, if a floatingfilm of oil or other liquid of reflectivity different from thereflectivity of the liquid of greater density passes through theapparatus, the intensity of reflected light striking the sample lightsensitive pickup means changes causing bridge circuit 33 to becomeunbalanced and transmit a signal to bridge amplifier 35. This signal isfiltered by capacitor filter 36, registered on signal meter 29, and may,if desired, be arranged to pass to the process alarm amplifier circuit34. If the signal exceeds the threshold magnitude of process alarmcircuit 34, this circuit element amplifies the signal so as to actuatealarm meter 28 giving an observer notice of the presence of the floatingliquid. The threshold magnitude of process alarm circuit 30 may beadjusted by regulating level adjust potentiometer 22 so that the circuitis activated by signals of varying magnitude depending upon thedifference in reflectivity to be expected between the less densefloating liquid and the liquid of greater density.

The embodiment of FIG. 1 may be afiixed to and supported by a buoyantsubstructure 38 which maintains light source 12 and sample pickup 16 atconstant elevations above liquid surface 39 to prevent movement of thereflected beam 44 away from the face of the sample pickup as the levelof the liquid to be tested changes. It is understood that where thelevel of the liquid to be tested does not vary the apparatus may befixedly supported above the surface of the liquid to be tested by otherappropriate means and that other level compensating support means may beused where liquid level does vary. It is also understood that while theembodiment of FIG. 1 may be operatively attached to aturbulence-reducing baffle means said baffle means, may, where needed,alternatively, be fixedly mounted below the apparatus in a channel orcontainer which carries the liquid to be tested.

In summary, this invention provides apparatus for detecting the presenceof a reflective liquid of lesser density floating on a more dense liquidof different reflectivity, comprising a light source 12, samplelight-sensitive pickup means 16 oriented to receive light from thesource that has been reflected from the surface of the liquid to betested, display means 28 for indicating the presence of a floating filmof differing reflectivity on the surface of the liquid to be tested, andcircuit means interconnecting the light-sensitive pickup means with thedisplay means. The circuit means may comprise an alarm amplifier circuit34 coupled to the sample pickup means, said alarm circuit being disposedto provide an output only if the input into the circuit varies from apreselected magnitude.

In the one embodiment of the invention a reference lightsensitive pickupmeans 17 may be positioned to received light directly from the lightsource. This reference light-sensitive means and the samplelight-sensitive pickup means may be operatively connected to the alarmamplifier circuit via a bridge circuit 33, said light-sensitive pickupmeans being disposed in adjacent legs of the bridge circuit.

The performance of the apparatus may be improved if a converging lens 13is interposed between the light source and the surface of the liquid tobe tested to cause approximately parallel rays of light to strike thesurface. The performance may be further improved if a converging lens 37is interposed between the sample light-sensitive pickup means and thesurface of the liquid to be tested.

Where necessary, the apparatus may be affixed to and supported by abuoyant substructure or float 38. If the invention is to be used wherethe surface of the liquid to be tested is not smooth, aturbulence-reducing baffle means 10, at least a portion of which extendsbeneath the surface of the liquid to be tested, may be operativelyconnected to the apparatus.

l claim as my invention:

1. Apparatus for monitoring a liquid surface of changing level to detectthe presence of a first reflective liquid floating on a secondreflective liquid of different reflectivity comprismg:

a light source oriented to project light onto a liquid surface to betested at a selected angle of incidence;

sample light-sensitive pickup means for measuring the intensity of lightreflected from the liquid surface oriented to receive light from thesource that has been reflected from the liquid surface at angle ofreflection equal to the selected angle of incidence, whereby said samplelightsensitive pickup means measures a first intensity indicative of thefirst reflective liquid when first reflective liquid is present on theliquid surface tested and a second, different, intensity indicative ofthe second reflective liquid when second reflective liquid is present onthe liquid surface tested;

display means responsive to the light intensity measured by the samplelight-sensitive pickup means for generating a signal indicating thepresence of the floating first reflective liquid when the samplelight-sensitive pickup means measures an intensity equal to said firstintensity;

circuit means interconnecting the sample light-sensitive pickup meanswith the display means; whereby when the sample light-sensitive pickupmeans measures a reflected light intensity equal to said firstintensity, the display means generates a signal indicating the presenceof the first reflective liquid; and

a buoyant substructure operatively connected to the light source andsample light-sensitive pickup means for supporting the light source andsample light-sensitive pickup means at a substantially constantelevation above the surface of the liquid to be tested, whereby thesample light sensitive pickup means continues to receive light from thesource reflected from the liquid surface at the selected angle ofincidence as the level of that surface changes.

2. The apparatus of claim 1 wherein the circuit means comprises an alarmamplifier circuit coupled to the sample lightsensitive pickup means,said alarm circuit including means to provide an output only if theinput into the alarm circuit from the sample light-sensitive pickupmeans varies from a preselected magnitude substantially equal to theinput into the alarm circuit when said sample light-sensitive pickupmeans is measuring an intensity equal to said second intensity to amagnitude substantially equal to the input into the alarm circuit whensaid sample light-sensitive pickup means is measuring an intensity equalto said first intensity.

3. The apparatus of claim 1 including reference light-sensitive pickupmeans for measuring a reference light intensity 5 and positioned toreceive light directly from the light source;

means for adjusting the intensity of light from the light sourcestriking the reference light-sensitive pickup means to change thereference light intensity; and operatively associated with the displaymeans, means for comparing light intensity measured by the samplelightsensitive pickup means with the reference light intensity measuredby the reference light-sensitive pickup means to detect changes in theamount of light reflected from 1 5 the liquid surface to be tested andthereby detect the presence of the floating first reflective liquid.

4. The apparatus of claim 3 wherein the means for compar ing lightintensity measured by the sample light-sensitive pickup means with thereference light intensity measured by the reference light-sensitivepickup means comprises:

a bridge circuit; said light-sensitive pickup means being connected inadjacent legs of the bridge circuit, whereby the balance of the bridgecircuit is changed when the intensity of light striking the samplelight-sensitive pickup means changes with respect to the intensity ofthe light striking the reference light-sensitive pickup means.

5. The apparatus of claim 1 further comprising a converging lensinterposed between the light source and the surface of the liquid to betested to cause approximately parallel rays of light to strike thesurface.

6. The apparatus of claim 3 further comprising a converging lensinterposed between the sample light-sensitive pickup means and thesurface of the liquid to be tested.

7. The apparatus of claim 1 further comprising a turbulence reducingbaffle means at least a portion of which extends beneath the surface ofthe liquid to be tested operatively connected to the apparatus.

8. The apparatus of claim 3 wherein the means for adjusting theintensity of light from the light source striking the 40 referencelight-sensitive pickup means comprises:

an opaque partition having an aperture therein positioned between thereference light-sensitive pickup means and the light source; and

adjustable aperture means associated with the aperture for adjusting theamount of light passing from the light source through the aperture tothe reference light-sensitive pickup means.

9. Apparatus for detecting the presence of a film of oil on a watersurface of changing level comprising:

an enclosed explosion-proof housing having at least one aperture in thebottom portion thereof positioned above the water surface;

a window covering the aperture;

a light source disposed in the housing to project light out of thehousing through the window onto a liquid surface to be tested at aselected angle of incidence;

a sample light-sensitive pickup means for measuring the intensity oflight reflected from the liquid surface disposed in the housing toreceive light from the source reflected from the liquid surface at anangle of reflection equal to the selected angle of incidence, saidsample light sensitive pickup means measuring a relatively highintensity when a film of oil is present on the liquid surface and arelatively low intensity when no film of oil is present on the liquidsurface;

display means responsive to the sample light-sensitive pickup means forindicating the presence of a floating film of oil on the water surfacewhen the measured intensity of the reflected light received by thesample lightsensitive pickup means exceeds a pre-selected value:

circuit means interconnecting the sample light-sensitive pickup meanswith the display means; said circuit means including means forgenerating a signal indicative of the presence of an oil film when thelight-sensitive pickup means measures a light intensity higher than thepreselected value; and

a buoyant substructure affixed to the enclosed explosion proof housingfor supporting the housing and enclosed light-source and samplelight-sensitive pickup means at a substantially constant elevation abovethe surface of the liquid to be tested, whereby the samplelight-sensitive pickup means continues to receive light from the sourcereflected from the liquid surface to be measured as the level of thatsurface changes.

10. The apparatus of claim 9 including:

reference light-sensitive pickup means disposed in the housing toreceive light directly from the light source;

light intensity adjusting means positioned in the housing between thelight source and the reference light-sensitive pickup means foradjusting the intensity of light striking the reference light-sensitivepickup means to a selected reference intensity; and wherein the meansfor generating a signal indicative of the justing means comprises:

an opaque partition having an aperture therein; and aperture adjustingmeans associated with the aperture for adjusting the amount of lightpassing from the light source through the aperture to the referencelight-sensitive pickup means.

1. Apparatus for monitoring a liquid surface of changing level to detectthe presence of a first reflective liquid floating on a secondreflective liquid of different reflectivity comprising: a light sourceoriented to project light onto a liquid surface to be tested at aselected angle of incidence; sample light-sensitive pickup means formeasuring the intensity of light reflected from the liquid surfaceoriented to receive light from the source that has been reflected fromthe liquid surface at angle of reflection equal to the selected angle ofincidence, whereby said sample light-sensitive pickup means measures afirst intensity indicative of the first reflective liquid when firstreflective liquid is present on the liquid surface tested and a second,different, intensity indicative of the second reflective liquid whensecond reflective liquid is present on the liquid surface tested;display means responsive to the light intensity measured by the sampleliGht-sensitive pickup means for generating a signal indicating thepresence of the floating first reflective liquid when the samplelight-sensitive pickup means measures an intensity equal to said firstintensity; circuit means interconnecting the sample light-sensitivepickup means with the display means; whereby when the samplelightsensitive pickup means measures a reflected light intensity equalto said first intensity, the display means generates a signal indicatingthe presence of the first reflective liquid; and a buoyant substructureoperatively connected to the light source and sample light-sensitivepickup means for supporting the light source and sample light-sensitivepickup means at a substantially constant elevation above the surface ofthe liquid to be tested, whereby the sample light sensitive pickup meanscontinues to receive light from the source reflected from the liquidsurface at the selected angle of incidence as the level of that surfacechanges.
 2. The apparatus of claim 1 wherein the circuit means comprisesan alarm amplifier circuit coupled to the sample light-sensitive pickupmeans, said alarm circuit including means to provide an output only ifthe input into the alarm circuit from the sample light-sensitive pickupmeans varies from a preselected magnitude substantially equal to theinput into the alarm circuit when said sample light-sensitive pickupmeans is measuring an intensity equal to said second intensity to amagnitude substantially equal to the input into the alarm circuit whensaid sample light-sensitive pickup means is measuring an intensity equalto said first intensity.
 3. The apparatus of claim 1 including referencelight-sensitive pickup means for measuring a reference light intensityand positioned to receive light directly from the light source; meansfor adjusting the intensity of light from the light source striking thereference light-sensitive pickup means to change the reference lightintensity; and operatively associated with the display means, means forcomparing light intensity measured by the sample light-sensitive pickupmeans with the reference light intensity measured by the referencelight-sensitive pickup means to detect changes in the amount of lightreflected from the liquid surface to be tested and thereby detect thepresence of the floating first reflective liquid.
 4. The apparatus ofclaim 3 wherein the means for comparing light intensity measured by thesample light-sensitive pickup means with the reference light intensitymeasured by the reference light-sensitive pickup means comprises: abridge circuit; said light-sensitive pickup means being connected inadjacent legs of the bridge circuit, whereby the balance of the bridgecircuit is changed when the intensity of light striking the samplelight-sensitive pickup means changes with respect to the intensity ofthe light striking the reference light-sensitive pickup means.
 5. Theapparatus of claim 1 further comprising a converging lens interposedbetween the light source and the surface of the liquid to be tested tocause approximately parallel rays of light to strike the surface.
 6. Theapparatus of claim 3 further comprising a converging lens interposedbetween the sample light-sensitive pickup means and the surface of theliquid to be tested.
 7. The apparatus of claim 1 further comprising aturbulence reducing baffle means at least a portion of which extendsbeneath the surface of the liquid to be tested operatively connected tothe apparatus.
 8. The apparatus of claim 3 wherein the means foradjusting the intensity of light from the light source striking thereference light-sensitive pickup means comprises: an opaque partitionhaving an aperture therein positioned between the referencelight-sensitive pickup means and the light source; and adjustableaperture means associated with the aperture for adjusting the amount oflight passing from the light source through the aperture to thereference light-sensItive pickup means.
 9. Apparatus for detecting thepresence of a film of oil on a water surface of changing levelcomprising: an enclosed explosion-proof housing having at least oneaperture in the bottom portion thereof positioned above the watersurface; a window covering the aperture; a light source disposed in thehousing to project light out of the housing through the window onto aliquid surface to be tested at a selected angle of incidence; a samplelight-sensitive pickup means for measuring the intensity of lightreflected from the liquid surface disposed in the housing to receivelight from the source reflected from the liquid surface at an angle ofreflection equal to the selected angle of incidence, said sample lightsensitive pickup means measuring a relatively high intensity when a filmof oil is present on the liquid surface and a relatively low intensitywhen no film of oil is present on the liquid surface; display meansresponsive to the sample light-sensitive pickup means for indicating thepresence of a floating film of oil on the water surface when themeasured intensity of the reflected light received by the samplelight-sensitive pickup means exceeds a pre-selected value; circuit meansinterconnecting the sample light-sensitive pickup means with the displaymeans; said circuit means including means for generating a signalindicative of the presence of an oil film when the light-sensitivepickup means measures a light intensity higher than the pre-selectedvalue; and a buoyant substructure affixed to the enclosed explosionproof housing for supporting the housing and enclosed light-source andsample light-sensitive pickup means at a substantially constantelevation above the surface of the liquid to be tested, whereby thesample light-sensitive pickup means continues to receive light from thesource reflected from the liquid surface to be measured as the level ofthat surface changes.
 10. The apparatus of claim 9 including: referencelight-sensitive pickup means disposed in the housing to receive lightdirectly from the light source; light intensity adjusting meanspositioned in the housing between the light source and the referencelight-sensitive pickup means for adjusting the intensity of lightstriking the reference light-sensitive pickup means to a selectedreference intensity; and wherein the means for generating a signalindicative of the presence of an oil film comprises a bridge circuitoperatively connecting the reference light-sensitive pickup means andthe sample light-sensitive pickup means to the display means, therespective light-sensitive pickup means being disposed in adjacent legsof the bridge circuit whereby the balance of the bridge circuit ischanged when the intensity of the light striking the samplelight-sensitive pickup means changes with respect to the referenceintensity of light striking the reference light-sensitive pickup means.11. The apparatus of claim 10 wherein the light intensity adjustingmeans comprises: an opaque partition having an aperture therein; andaperture adjusting means associated with the aperture for adjusting theamount of light passing from the light source through the aperture tothe reference light-sensitive pickup means.